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United States. Growing season April–October, harvest usually September–October. 26 vintages of weather, 2000–2025.
Photo: Rhododendrites, CC BY-SA 4.0, via Wikimedia Commons
Over the 30 growing seasons from 1991 to 2020, Napa Valley's vines saw on average 1,930 growing degree days between April and October. That puts it in Winkler region III, close in heat and rain to Paso Robles, Maipo Valley and McLaren Vale. In a typical year about 107 mm of rain falls in the growing season, 37 mm of it in September–October.
Since 2000 the warmest season was 2020 (+20% against normal) and the coolest 2010 (-11%). The wettest harvest window was 2021, with 176 mm against a normal 37 mm.
The last 10 vintages (2016–2025) averaged +8% against the 1991–2020 normal, compared with -2% for 2000–2009; 7 of those 10 seasons were warmer than normal by more than 3%.
Growing degree days (base 10°C) for each season. The dashed line is the 1991–2020 normal (1,930 GDD) and the shaded band one standard deviation either side: about two years in three fall inside it.
Full bar: rain over the whole growing season. Dark part: rain in the harvest window (September–October). The line is the normal season total, 107 mm.
Apr–Oct 2025
Near normal
Hot months: May +2.5°
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 10 of 26 for heat · Winkler IV
Apr–Oct 2024
Much warmer
Hot months: Jun +2.4° Jul +3.9° Oct +3.5°
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 2 of 26 for heat · Winkler V
Apr–Oct 2023
Near normal
Hot months: Aug +2.0°
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 14 of 26 for heat · Winkler III
Apr–Oct 2022
Much warmer
Hot months: May +2.3° Jun +2.3° Sep +2.1°
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 4 of 26 for heat · Winkler IV
Apr–Oct 2021
Warmer
Hot months: Apr +2.4° May +2.9°
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 8 of 26 for heat · Winkler IV
Apr–Oct 2020
Much warmer
Hot months: Aug +2.5° Sep +2.6° Oct +4.7°
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 1 of 26 for heat · Winkler V
Apr–Oct 2019
Much warmer
Hot months: Aug +2.0°
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 5 of 26 for heat · Winkler IV
Apr–Oct 2018
Warmer
Hot months: Jun +2.1°
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 9 of 26 for heat · Winkler IV
Apr–Oct 2017
Much warmer
Hot months: Jul +2.4°
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 3 of 26 for heat · Winkler IV
Apr–Oct 2016
Near normal
No month ran 2°C above its normal high
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 13 of 26 for heat · Winkler IV
Apr–Oct 2015
Warmer
Hot months: Oct +2.8°
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 7 of 26 for heat · Winkler IV
Apr–Oct 2014
Much warmer
Hot months: May +2.3°
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 6 of 26 for heat · Winkler IV
Apr–Oct 2013
Near normal
Hot months: Apr +3.1°
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 12 of 26 for heat · Winkler IV
Apr–Oct 2012
Cooler
No month ran 2°C above its normal high
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 23 of 26 for heat · Winkler III
Apr–Oct 2011
Much cooler
No month ran 2°C above its normal high
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 25 of 26 for heat · Winkler III
Apr–Oct 2010
Much cooler
No month ran 2°C above its normal high
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 26 of 26 for heat · Winkler III
Apr–Oct 2009
Cooler
No month ran 2°C above its normal high
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 20 of 26 for heat · Winkler III
Apr–Oct 2008
Near normal
No month ran 2°C above its normal high
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 16 of 26 for heat · Winkler III
Apr–Oct 2007
Cooler
No month ran 2°C above its normal high
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 22 of 26 for heat · Winkler III
Apr–Oct 2006
Near normal
Hot months: Jul +2.4°
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 18 of 26 for heat · Winkler III
Apr–Oct 2005
Cooler
No month ran 2°C above its normal high
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 24 of 26 for heat · Winkler III
Apr–Oct 2004
Near normal
No month ran 2°C above its normal high
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 15 of 26 for heat · Winkler III
Apr–Oct 2003
Near normal
Hot months: Oct +2.4°
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 17 of 26 for heat · Winkler III
Apr–Oct 2002
Near normal
No month ran 2°C above its normal high
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 19 of 26 for heat · Winkler III
Apr–Oct 2001
Near normal
Hot months: May +5.1°
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 11 of 26 for heat · Winkler IV
Apr–Oct 2000
Cooler
No month ran 2°C above its normal high
Bars: mean daily high each month (red = 2°C or more above normal, blue = that much below). Line: the 1991–2020 normal.
Rank 21 of 26 for heat · Winkler III
| Vintage | GDD | vs normal | Season rain | Harvest rain | Hottest month (mean high) |
|---|---|---|---|---|---|
| 2025 | 1,990 | +3% | 75 mm | 66 mm | August 32.5°C |
| 2024 | 2,240 | +16% | 62 mm | 6 mm | July 34.6°C |
| 2023 | 1,930 | -0% | 45 mm | 13 mm | August 32.9°C |
| 2022 | 2,150 | +11% | 78 mm | 40 mm | August 32.7°C |
| 2021 | 2,030 | +5% | 185 mm | 176 mm | July 31.3°C |
| 2020 | 2,330 | +20% | 48 mm | 0 mm | August 33.4°C |
| 2019 | 2,100 | +9% | 91 mm | 3 mm | August 32.9°C |
| 2018 | 2,000 | +3% | 77 mm | 16 mm | July 32.0°C |
| 2017 | 2,180 | +12% | 73 mm | 9 mm | July 33.1°C |
| 2016 | 1,950 | +1% | 210 mm | 150 mm | July 30.7°C |
| 2015 | 2,050 | +6% | 55 mm | 14 mm | September 31.5°C |
| 2014 | 2,090 | +8% | 68 mm | 37 mm | June 30.4°C |
| 2013 | 1,970 | +2% | 49 mm | 12 mm | July 30.0°C |
| 2012 | 1,810 | -6% | 79 mm | 27 mm | August 30.8°C |
| 2011 | 1,740 | -10% | 133 mm | 44 mm | September 31.4°C |
| 2010 | 1,720 | -11% | 210 mm | 93 mm | September 31.1°C |
| 2009 | 1,870 | -3% | 161 mm | 110 mm | September 31.7°C |
| 2008 | 1,920 | -1% | 37 mm | 25 mm | August 31.4°C |
| 2007 | 1,820 | -6% | 107 mm | 59 mm | August 30.5°C |
| 2006 | 1,900 | -2% | 186 mm | 11 mm | July 33.1°C |
| 2005 | 1,790 | -7% | 138 mm | 9 mm | July 32.2°C |
| 2004 | 1,930 | -0% | 110 mm | 97 mm | September 30.4°C |
| 2003 | 1,920 | -1% | 124 mm | 2 mm | July 32.3°C |
| 2002 | 1,880 | -3% | 30 mm | 2 mm | July 31.2°C |
| 2001 | 1,980 | +3% | 63 mm | 34 mm | August 31.0°C |
| 2000 | 1,860 | -4% | 174 mm | 83 mm | August 30.9°C |
| 1991–2020 | 1,930 | ±7% (1 SD) | 107 mm | 37 mm |
The closest matches on this site by normal heat and season rain. Similar weather is one ingredient; soils, slopes and grapes differ.
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